Neutrony

Neutrony (English: neutrons) are neutral subatomic particles and one of the basic constituents of atomic nuclei, along with protons. Each neutron has spin 1/2 and a mass slightly larger than that of a proton. Its electric charge is zero, making it electrically neutral.

Neutrons are composed of three quarks (one up and two down) bound by the strong force. In atomic nuclei they contribute to the binding energy that holds nuclei together, while the number of neutrons relative to protons determines the isotope and stability of an element.

Free neutrons are unstable and decay by beta decay into a proton, an electron, and an antineutrino with a mean lifetime of about 880 seconds (roughly 14.7 minutes). Within most nuclei, neutrons can be stable due to binding energy, though many isotopes are radioactive and decay by beta emission or other processes.

Neutrons interact with matter primarily via the strong and weak nuclear forces. They do not interact electromagnetically, which makes them highly penetrating. They can be slowed (moderated) by scattering in light elements, enabling sustained nuclear chain reactions in reactors and weapons. Neutron absorption and scattering cross sections vary with energy and target nucleus; detection relies on materials such as helium-3, boron-10, or scintillators.

Applications include neutron scattering and diffraction for determining material structures, neutron activation analysis, and medical therapies that use neutrons. In astrophysics, neutrons are central to the physics of neutron stars and certain stellar processes.

Neutrons were discovered by James Chadwick in 1932, following earlier work on radiation. The discovery led to the development of nuclear reactors, radiography, and many areas of fundamental and applied science.